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Jame's TPN Recipe?

JenCliBee

JenCliBee

Member
Joined
30 Mar 2009
Messages
533
Location
W.Midlands
Hi peeps, i have a question.... it may sound obvious but i really dont know lol.


James TPN mix as follows....

48g Potassium Nitrate
2.2g Potassium Phosphate (monobasic)
17g Magnesium Sulphate Heptahydrate (Epsom Salts)
0.5g E300 Ascorbic Acid
0.2g E202 Potassium Sorbate
5g EDTA Chelated Trace Elements Mix (TNC Trace, CSM+B)
500ml distilled water

Right then, i haven't got any acorbic acid or pat sorbate, so with this in mind, would i be thinking that i would need to make the trace mix separate to the macro mix...

I.E .... mix the amount of trace stated in 500ml of water in one bottle and then mix the stated amounts of Potassium Nitrate, Potassium Phosphate, Magnesium Sulphate Heptahydrate in 500ml of water in a separate bottle.... avoiding the need for the missing ingredients?...... would there be any deteroation problems by doing it the above way? untill i do an order for more powders.


Ive only ever used EI dosing or the full TPN+ mix so unsure if the above would be the way to go considering i dont have the 2 powders above?.

Thanks

Jen
 
Themuleous said:
I dont honestly know, but your reasoning seems sensible. Perhaps try and see?

Sam
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Thanks for the reply mate, will give it a go... cant see any problems myself :)


Yes do it separately, absorbic acid and p. sorbate are not needed then.
Click to expand...

Cheers for the confirmation.... will get mixing in a bit lol.


Thanks again
 
Err..this doesnt make sense to me. The whole point of the acids is to allow the phospates and iron to coexist without bonding and falling out of solution. Without their presence it's unwise to dose the two together so you're back to EI scheme of alternate dosing, so whats the point? You can't get something for nothing...

Cheers,
 
ceg4048 said:
Err..this doesnt make sense to me. The whole point of the acids is to allow the phospates and iron to coexist without bonding and falling out of solution. Without their presence it's unwise to dose the two together do you're back to EI scheme of alternate dosing, so whats the point? You can't get something for nothing...

Cheers,
Click to expand...


So dosing the macro and trace on alternate days... (i guess would work in a similar way EI is dosed?) would get around this problem then, Yes?.

The reasoning behind doing it this way...as ive already put on the first post was i dont have the 2 powders to make this mix an all in one.... i also dont need to make any orders yet from anywhere to add these missing items... so ordering just these wouldn't make sense.

I'm not trying to get anything for nothing, just thought this would be a feasible way of doing things untill i make my next order so i can add the items im missing.

Just a simple explanation without the flippancy would have been nice for a change mate :rolleyes: .
 
Hi all,
I'm not sure whether you can still get citric acid at a chemists, but you used to be able to, any acid would potentially do as it is only to keep the pH below pH7 in the solution. I'm also pretty sure "Distilled Malt vinegar" would work, it is the clear vinegar you can get at Sainsbury's etc.

Potassium sorbate you can get from a "home brew" shop, if you can still find one. You only need it if you are going to keep the solution for a long time, it stops moulds etc growing and it isn't essential.

cheers Darrel
 
dw1305 said:
Hi all,
I'm not sure whether you can still get citric acid at a chemists, but you used to be able to, any acid would potentially do as it is only to keep the pH below pH7 in the solution. I'm also pretty sure "Distilled Malt vinegar" would work, it is the clear vinegar you can get at Sainsbury's etc.

Potassium sorbate you can get from a "home brew" shop, if you can still find one. You only need it if you are going to keep the solution for a long time, it stops moulds etc growing and it isn't essential.

cheers Darrel
Click to expand...


Thanks DW, will have to see if i can find what you suggested from the chemist, i will buy the proper stuff listed once i make an order that's worth making lol.

The solution doesn't really last to long tbh so yes i probably wouldn't have a problem leaving out the P sorbate.

However without adding either and making the solutions separate (as i already have) would dosing on alternate days be a feasible option to avoid as Clive has put .....

"phospates and iron to coexist without bonding and falling out of solution"
Click to expand...
?.


I will need to order more ferts within the next couple weeks anyways amongst a couple of other things, so will be ordering the whole ingredients to avoid any of my above questions. It's really just something to tie me over till then lol.
 
Hi all,
Yes, you can dose alternate days, as Clive says the problem is that a lot of phosphate compounds are insoluble. As an example calcium phosphate forms "bone". If you keep the pH below pH7 these insoluble compounds don't form.

Iron is another problem as most of its compounds are insoluble and it is very difficult to keep in solution. This is why we have to use chelated Iron, these chelates are stable and the iron would be unavailable, but fortunately they are degraded by light, trickling out iron ions.

The problem is that the plant can only take up ions (K+, NO3- etc.), so these have to be in solution for the plant to use them. As soon as Ca2+ and PO43- form Ca3(PO4)2 they are unavailable to the plant, and will remain so unless the solution becomes acid enough for them to disassociate into ions again.

Hope that makes sense.

cheers Darrel
 
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